The Deduplication Engine service can potentially take some time to start up, depending on the contents of your deduplication storage. If you change the service startup mode to delayed-auto, it shouldn't prevent you from logging in while the Dedupe Engine is starting.

Running this command from your Windows CLI should help:

sc config spoold start= delayed-auto

NOTE: The delayed-auto is not available on Windows 2003, but since you're running Win 2k8, you should be ok.